The present invention relates to a visual display paging system which consist of one or more message input stations and one or more illuminated remote visual display stations for communicating messages to viewers. The present invention more particularly relates to a method for providing power and data exchange to a remote visual display over the same wire pair, especially to a method for sending message data which is rectified for power to drive a remote visual display and at the same time allowing the master message input station to receive message input data from slave input message stations connected to the same wire pair. This invention allows for a plurality of both input stations and output stations. These remote visual display paging systems may display either moving or stationary messages. There may be one or more slave message input stations that convey the message entered in a slave message input location to the master message station for eventual display on the remote visual display(s). The master message input station may store and sequentially display several messages or pages.
It has become more important in recent times to provide a simple, easy visual paging system to page a single person from a group of people. This person could be located in a crowd in an auditorium or in a restaurant or in a retail store. This type of visual paging system typically has the display located some distance from the message input station. In an auditorium or church the message input station may be in the sound control room or the nursery. The remote visual display is in front of the audience. The visual display paging system can be used to page a doctor to the phone or a mother to the nursery to attend to her child. The remote visual display is typically 100 to 400 feet away from the master message input station. In the restaurant application the remote visual displays may be in several eating areas some distance from the food pick-up area where the message input station is located. The visual display paging system could be used to page a customer or waitress to the food pick-up areas. In a retail store the message input station is typically located in a supervisors office while the displays are located through out the store and are easily visible by the store clerks. Store clerks or security personnel may be easily paged. Store systems can range up to 1000 feet between the input message station and the remote visual displays located where they can be seen by everyone.
Remote visual displays require both power and signal to operate. First, power must be supplied to operate both the display mechanism (light sources or light reflectors) and the serial data decoding circuits. Second, the serially encoded electrical signal conveying the message to be displayed must be supplied from an input station, computer or other source. Thirdly, provision must be made for data exchange between the master message input station and the slave message input stations.
The early installations of these displays required one wire between the message input station and the remote visual display for each visual element or light on the message board and one common return wire. The power required for the luminaire apparatus was supplied through these control wires from the input station. The message input station must be connected to the a-c power line or some source of power. This type installation is very expensive and time consuming. A typical installation required 15 wires and only displayed two numbers. Also, possible damage can result from miswiring.
Later developments in the art refined the system to require only one wire pair for the power and another wire pair for the signal. The serial signal sent by the message input station to the remote visual display is decoded and applied to the proper luminaire apparatus. A-C power must be provided to both the message input station and to the remote visual display. Although an improvement, this required four wires between the message input station and the remote visual display. Wire expense and the possibility of the installer damaging the system with mixed up wires during installation is a disadvantage. This happens often when the purchaser who is not skilled in the art installs his own system such as the case with a church. This has the further disadvantage in that if the power supply wires connect to a nearby a-c outlet then provision must be made to disconnect the power when the system is not in use. If the power wires come from a great distance then there is additional expenses because of the power supply wire length. The more sophisticated paging systems which accommodated one or more slave message input stations required a third wire pair for data exchange between the master message input station and the slave message input stations.